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The short-chain fatty acids (SCFAs) butyrate, propionate and acetate are microbial metabolites and their availability in the gut and other organs is determined by environmental factors, such as diet and use of antibiotics, that shape the diversity and metabolism of the microbiota. SCFAs regulate epithelial barrier function as well as mucosal and systemic immunity via evolutionary conserved processes that involve G protein-coupled receptor signalling or histone deacetylase activity. Indicatively, the anti-inflammatory role of butyrate is mediated through direct effects on the differentiation of intestinal epithelial cells, phagocytes, B cells and plasma cells, and regulatory and effector T cells. Intestinally derived SCFAs also directly and indirectly affect immunity at extra-intestinal sites, such as the liver, the lungs, the reproductive tract and the brain, and have been implicated in a range of disorders, including infections, intestinal inflammation, autoimmunity, food allergies, asthma and responses to cancer therapies. An ecological understanding of microbial communities and their interrelated metabolic states, as well as the engineering of butyrogenic bacteria may support SCFA-focused interventions for the prevention and treatment of immune-mediated diseases., (© 2024. Springer Nature Limited.)

Background and Aims: Major genomic drivers of hepatocellular carcinoma (HCC) are nowadays well recognized, although models to establish their roles in human HCC initiation remain scarce. Here, we used human liver organoids in experimental systems to mimic the early stages of human liver carcinogenesis from the genetic lesions of TP53 loss and L3 loop R249S mutation. In addition, chromatin immunoprecipitation sequencing (ChIP-seq) of HCC cell lines shed important functional insights into the initiation of HCC consequential to the loss of tumor-suppressive function from TP53 deficiency and gain-of-function activities from mutant p53., Approach and Results: Human liver organoids were generated from surgical nontumor liver tissues. CRISPR knockout of TP53 in liver organoids consistently demonstrated tumor-like morphological changes, increased in stemness and unrestricted in vitro propagation. To recapitulate TP53 status in human HCC, we overexpressed mutant R249S in TP53 knockout organoids. A spontaneous increase in tumorigenic potentials and bona fide HCC histology in xenotransplantations were observed. ChIP-seq analysis of HCC cell lines underscored gain-of-function properties from L3 loop p53 mutants in chromatin remodeling and overcoming extrinsic stress. More importantly, direct transcriptional activation of PSMF1 by mutant R249S could increase organoid resistance to endoplasmic reticulum stress, which was readily abrogated by PSMF1 knockdown in rescue experiments. In a patient cohort of primary HCC tumors and genome-edited liver organoids, quantitative polymerase chain reaction corroborated ChIP-seq findings and verified preferential genes modulated by L3 mutants, especially those enriched by R249S., Conclusions: We showed differential tumorigenic effects from TP53 loss and L3 mutations, which together confer normal hepatocytes with early clonal advantages and prosurvival functions., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background and Objective: Hong Kong, like many parts of Asia, faces a high burden of hepatocellular carcinoma (HCC) caused by high endemic rates of hepatitis B virus infection. Hong Kong clinicians have developed a high level of expertise in HCC treatment across surgical, transarterial, ablative, radiotherapeutic and systemic modalities. This publication summarizes the latest evidence-based recommendations on how these modalities should be used., Methods: In two meetings held in 2020, a multidisciplinary panel of surgeons, oncologists and interventional radiologists performed a narrative review of evidence on the management of HCC, with an emphasis on treatment of HCC not amenable to surgical resection. Close attention was paid to new evidence published since the previous version of these statements in 2018., Key Content and Findings: The expert panel has formulated 60 consensus statements to guide the staging and treatment of unresectable HCC. Since the previous version of these statements, considerable additions have been made to the recommendations on use of targeted therapies and immunotherapies because of the large volume of new evidence., Conclusions: Our consensus statements offer guidance on how to select HCC patients for surgical or non-surgical treatment and for choosing among non-surgical modalities for patients who are not candidates for resection. In particular, there is a need for more evidence to aid physicians in the selection of second-line systemic therapies, as currently most data are limited to patients with disease progression on first-line sorafenib., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-21-405/coif). TTC has received research funding from Eisai for medical writing and for funding support to an investigator-initiated study, and study support from BMS for provision of drug to an investigator-initiated study. SC has received research grants from Bayer, MSD, Eisai, Sirtex, and Ipsen, consulting fees from Novartis, MSD, Eisai, AstraZeneca, and Bristol Myers Squibb, and speaking honoraria from Bayer, Astra-Zeneca, Eisai, Roche, and MSD. TY has received research funding from Bayer, Eisai and Ipsen and speaking honoraria from Bristol Myers Squibb, Eisai, Ipsen, MSD, AstraZeneca, and Bayer. The other authors have no conflicts of interest to disclose., (2023 Hepatobiliary Surgery and Nutrition. All rights reserved.)

Hermansky-Pudlak syndrome (HPS) types 1 and 4 are caused by defective vesicle trafficking. The mechanism for Crohn's disease-like inflammation, lung fibrosis, and macrophage lipid accumulation in these patients remains enigmatic. The aim of this study is to understand the cellular basis of inflammation in HPS-1. We performed mass cytometry, proteomic and transcriptomic analyses to investigate peripheral blood cells and serum of HPS-1 patients. Using spatial transcriptomics, granuloma-associated signatures in the tissue of an HPS-1 patient with granulomatous colitis were dissected. In vitro studies were conducted to investigate anti-microbial responses of HPS-1 patient macrophages and cell lines. Monocytes of HPS-1 patients exhibit an inflammatory phenotype associated with dysregulated TNF, IL-1α, OSM in serum, and monocyte-derived macrophages. Inflammatory macrophages accumulate in the intestine and granuloma-associated macrophages in HPS-1 show transcriptional signatures suggestive of a lipid storage and metabolic defect. We show that HPS1 deficiency leads to an altered metabolic program and Rab32-dependent amplified mTOR signaling, facilitated by the accumulation of mTOR on lysosomes. This pathogenic mechanism translates into aberrant bacterial clearance, which can be rescued with mTORC1 inhibition. Rab32-mediated mTOR signaling acts as an immuno-metabolic checkpoint, adding to the evidence that defective bioenergetics can drive hampered anti-microbial activity and contribute to inflammation., (© 2022. The Author(s).)

Epidemiological and associative research from humans and animals identifies correlations between the environment and health impacts. The environment-health inter-relationship is effected through an individual's underlying genetic variation and mediated by mechanisms that include the changes to gene regulation that are associated with the diversity of phenotypes we exhibit. However, the causal relationships have yet to be established, in part because the associations are reduced to individual interactions and the combinatorial effects are rarely studied. This problem is exacerbated by the fact that our genomes are highly dynamic; they integrate information across multiple levels (from linear sequence, to structural organisation, to temporal variation) each of which is open to and responds to environmental influence. To unravel the complexities of the genomic basis of human disease, and in particular non-communicable diseases that are also influenced by the environment (e.g., obesity, type II diabetes, cancer, multiple sclerosis, some neurodegenerative diseases, inflammatory bowel disease, rheumatoid arthritis) it is imperative that we fully integrate multiple layers of genomic data. Here we review current progress in integrated genomic data analysis, and discuss cases where data integration would lead to significant advances in our ability to predict how the environment may impact on our health. We also outline limitations which should form the basis of future research questions. In so doing, this review will lay the foundations for future research into the impact of the environment on our health., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Noble, Purcell, Adams, Lam, Ring, Anderson and Osborne.)

Background: Topical immunotherapy has recently been found useful in the treatment of chronic and extensive Alopecia Areata (AA)., Objective: To evaluate the efficacy and safety of diphenylcyclopropenone (DPCP) use among Chinese patients with steroid resistant and extensive AA in our institute., Methods: The medical records of 31 Chinese patients treated with DPCP were analysed retrospectively. The efficacy, adverse effects, and relapse rate of DPCP treatment were reviewed., Results: Thirty-one (16 male, 15 female) Chinese patients with extensive, steroid resistant Alopecia Areata and a mean age of 28.9 years (SE 10.4) were treated. The mean age of onset was 17.8 years (SE 8.8) with an average disease duration of 11.2 years (SE 7.7). Ten patients had a history of atopy and 4 had a history of thyroid disease. Nail changes were found in 14 patients and a family history of AA was found in 2 patients. Thirteen patients (41.9%) had experienced total hair loss. Two patients abandoned the treatment due to severe side effects. Of the remaining 29 patients, 4 (13.8%), 7 (24.1%), 5 (17.2%), and 13 (44.8%) achieved >90% complete response, >50-90% partial response, >10-50% minimal response, and <10% no response hair regrowth, respectively. Adverse effects included pruritus, erythema, vesiculation, scaling, cervical lymphadenopathy, dyspigmentation and urticarial reactions. Relapse occurred (>25% hair loss) in 69.23% of patients after 18 months of follow up., Conclusions: DPCP is an effective and tolerable treatment for Chinese patients with extensive, steroid resistant AA., (© 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.)

Objective: Significant weight gain is a problematic side effect of treatment with the antipsychotic drug olanzapine (OLA). Previous studies in rats suggest that one of the contributing factors is an impairment in satiation that results in increased food intake. However, the mechanisms underlying this impairment in satiation remain largely unclear., Methods and Results: In this study, we determined the effect of OLA on levels of leptin, insulin, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1, peptide YY and amylin in male rats that had received a fixed amount of food. OLA did not affect the secretion of any of these hormones, except for ghrelin levels, which were increased compared with controls. Furthermore, when ghrelin levels were determined in rats just before they received their meal, OLA caused a significant increase in ghrelin levels compared with controls, whereas OLA failed to affect baseline ghrelin levels. Next, we investigated the effect of OLA on the efficacy of CCK to reduce meal size. With coadministration, OLA pretreatment counteracted the reduction in meal size by CCK, although there was no significant interaction between the treatments. Finally, telemetry measurements revealed that acute OLA treatment causes a temporary decrease in both locomotor activity and body core temperature., Conclusion: Taken together, this study shows that acute injection of OLA selectively increases meal-related ghrelin secretion and this may partially underlie the impairment in satiation by OLA.

OBJECTIVE. To serially evaluate the viral kinetics of occult hepatitis B virus infection in lymphoma patients and perform a correlation with clinical outcomes. DESIGN. Case series with 1-year follow-up. SETTING. Regional hospital, Hong Kong. PATIENTS. Consecutive patients who were newly diagnosed to have lymphoma in the hospital between 1 April 2007 and 31 March 2008 were tested for hepatitis B (HB) surface (s) antigen (Ag), anti-HBs antibody (Ab) and anti-HB core (c) Ab. Seropositive occult hepatitis B patients as defined by being negative for HBsAg but positive anti-HBsAb and/or anti-HBcAb without a hepatitis B vaccination history were recruited. Serum HBsAg, anti-HBsAb, anti-HBcAb, hepatitis B virus deoxyribonucleic acid (DNA) level, and liver biochemistry were checked at baseline and every 4 weeks during and after chemotherapy until 12 months after the completion of chemotherapy or death. Entecavir was started if patients developed biochemical flare-up of hepatitis B associated with virological rebound. The prevalence and course of hepatitis B virus-related hepatitis, as well as any temporal relationship to viral kinetics and clinical hepatitis, were assessed. RESULTS. Of 47 patients tested, 10 (21%) with lymphoma were seropositive occult hepatitis carriers. Their median baseline hepatitis B virus DNA level was 89 IU/mL (range, <34-807 IU/mL). Virological rebound (as defined by a 10-fold increase in serum hepatitis B virus DNA level from pre-chemotherapy level persisted for 4 weeks) occurred in one of the 10 patients, followed by biochemical reactivation. Whereupon entecavir treatment was started and no liver failure ensued. Regarding the other seropositive occult patients, their serum hepatitis B virus DNA levels fluctuated, but there was no associated biochemical reactivation. CONCLUSION. Detectable baseline serum hepatitis B virus DNA is not uncommon in patients with occult hepatitis B who receive chemotherapy. Transient elevation in serum hepatitis B virus DNA levels does not predict biochemical reactivation, but antiviral treatment might be considered if virological rebound persists.

Background: The present study investigates the effects of ginsenosides Rh1 and Rg2 against 6-hydroxydopamine (6-OHDA), a neurotoxin on SH-SY5Y cells and PC-12 cells. The effects of these two ginsenosides on neuronal differentiation are also examined., Methods: LDH assay was used to measure cell viability after exposure to 6-OHDA and ginsenosides. Neuronal differentiation was evaluated by changes in cell morphology and density of neurite outgrowths. Western blotting was used to determine the ginsenosides' effects on activation of extracellular signal-regulated protein kinases (ERKs)., Results: Rh1 and Rg2 attenuated 6-OHDA toxicity in SH-SY5Y cells and induced neurite outgrowths in PC-12 cells. 6-OHDA-induced ERK phosphorylation was decreased by Rh1 and Rg2. 20(R)-form and 20(S)-form of the ginsenosides exerted similar effects in inducing neurite outgrowths in PC-12 cells., Conclusion: The present study demonstrates neuroprotective effects of ginsenosides Rh1 and Rg2 on neuronal cell lines. These results suggest potential Chinese medicine treatment for neurodegenerative disorders (eg Parkinson's disease).

Objective: The aim of this study was to better understand the knowledge of schizophrenia, preferences regarding professional help, medication and treatment methods among Australians of a Chinese-speaking background., Methods: A cluster convenience sampling method was adopted in which subjects were taken from the four main areas in cosmopolitan Melbourne where most Chinese people live. A total of 200 Chinese-speaking Australians participated in the study. They were presented with a vignette describing an individual with schizophrenia and were then asked questions to assess their understanding of schizophrenia and their preferences regarding professional help, medication and treatment methods. A comparative approach was used to compare our findings with those of a previous study on the mental health literacy of Australian and Japanese adults., Results: Compared with the Australian and Japanese samples, a much lower percentage of Chinese-speaking Australians (15.5%) was able to identify the vignette as a case of schizophrenia/psychosis. A higher percentage of the Chinese-speaking Australians believed that professionals, and particularly counselling professionals, could be helpful for the person in the vignette. A higher percentage of the Chinese-speaking Australian and Japanese samples believed that close family members could be helpful, and expressed more uncertainty about the usefulness or harmfulness of certain medications than the Australian sample. A higher percentage of the Chinese-speaking Australians than the Australian and Japanese samples endorsed inpatient treatment for the person in the vignette. About 22, 17, 19 and 28% of the Chinese-speaking Australian participants, respectively, rated 'traditional Chinese medical doctors', 'Chinese herbal medications', 'taking Chinese nutritional foods/supplements' and 'qiqong' as helpful. Many perceived 'changing fungshui' and 'traditional Chinese prayer' to be harmful., Conclusions: Campaigns to increase the schizophrenia literacy of Chinese-speaking Australians are needed and must take into consideration the aforementioned socially and culturally driven beliefs so that culturally relevant education programmes can be developed.

Background: This study investigated the knowledge of depression and preference for professional help, medications and treatment methods among Australians of Chinese-speaking background, and the perceptions of this population of the causes of mental illness., Methods: Adopting a cluster convenience sampling method, the study recruited 200 Chinese-speaking subjects from four major areas in metropolitan Melbourne where many Chinese live. The respondents were presented with a vignette describing an individual with depression and then asked questions to assess their understanding of depression and preference for professional help, medications and treatment methods. A comparative approach was used to compare the findings with those of a previous study of the mental health literacy of Australian and Japanese adults., Results: Compared to the Australian and Japanese samples, a much lower percentage of Chinese-speaking Australians (14%) could correctly identify major depression described in the vignette, and a higher percentage believed that counseling professionals could be helpful. Higher percentages of those who believed that close family members could be helpful were found in the Chinese-speaking Australian and Japanese samples, and these two groups also expressed more uncertainty about the usefulness or harmfulness of certain medications compared to the Australian sample. Higher percentages of respondents in both the Chinese-speaking Australian and the Australian sample considered "lifestyle changes" to be helpful compared to the Japanese sample. In the Chinese-speaking sample, 30%, 17.4%, 33% and 27% of the respondents rated "traditional Chinese medicine doctors," "Chinese herbal medications," "taking Chinese nutritional foods/supplements" and "qiqong" as helpful. Many perceived "changing fungshui" and "traditional Chinese worship" to be harmful. Regarding the perception of causes of mental illness, items related to psychosocial perspectives including "life stress" and "interpersonal conflict" were rated highly by the respondents, whereas traditional beliefs including "punishment for misdeeds conducted by ancestors" and "demon possession" had the lowest ratings., Conclusions: Campaigns to increase the mental health literacy of Chinese-speaking Australians are needed. The above-mentioned socially and culturally driven beliefs need to be taken into consideration in the development of culturally relevant education programs.

Transcranial Doppler sonography (TCD) of cerebrovascular reactivity has been used to study migraine interictally. However, the previous TCD findings had been quite varied at the post breath-hold period. Autonomic responses were usually studied with cardiac information. The aim of this study was to use TCD as a tool to examine difference in cerebrovascular reactivity between migraineurs and non-headache controls by measuring interictally the whole time course of cerebral blood flow velocity (CBFV) during and after a breath-hold challenge. The percentage change of CBFV was derived in the left and right middle cerebral arteries in 10 migraineurs and 10 controls during and after a 20 s breath-hold. Three phases of CBFV change were identified with an initial positive phase above baseline, a middle negative phase during breath-hold, and a late positive phase which started before the cessation of breath-hold and continued for a period after. In addition to CBFV, we also extracted and utilized the information of the cardiac cycle duration (CC) derived from the time course of CBFV. The percentage change of CC was derived from time intervals between every two points of inflexion in CBFV. Two undershoots of CC change were shown at the transitions of breathing motions. We found evidence that migraineurs had significant difference of CBFV change at the middle negative phase during breath-hold and the pronounced undershoots of CC change compared to non-headache controls.

An otherwise well 70-year-old man presented with a non-specific complaint of epistaxis caused by an underlying necrotic natural killer-cell lymphoma complicated by a maggot infestation. He failed to attend for treatment after discharge but re-presented 3 weeks later with an acute exacerbation of his chronic pulmonary obstructive disease. During those 3 weeks his nasal condition had advanced rapidly with extensive tumour infiltration and necrosis affecting his nose and face. The natural clinical course, overall prognosis, and available treatment modalities are briefly discussed.

This study (1) compared the curing-light intensity with various barrier infection-control methods used to prevent cross contamination, (2) compared the Knoop hardness value of cured composite resin when various barrier control methods were used, and (3) correlated the hardness of the composite resin with the light-intensity output when different infection-control methods were used. The light-cure unit tips were covered with barriers, such as cellophane wrap, plastic gloves, Steri-shields, and finger cots. The control group had no barrier. Composite resins were then cured for each of the five groups, and their Knoop hardness values recorded. The results showed that there was significant statistical difference in the light-intensity output among the five groups. However, there was no significant statistical difference in the Knoop hardness values among any of the groups. There was also no correlation between the Knoop hardness value of the composite resin with the light-intensity output and the different infection-control methods. Therefore, any of the five infection-control methods could be used as barriers for preventing cross-contamination of the light-cure unit tip, for the light-intensity output for all five groups exceeded the recommended value of 300 W/m2. However, to allow a greater margin of error in clinical situations, the authors recommend that the plastic glove or the cellophane wrap be used to wrap the light-cure tip, since these barriers allowed the highest light-intensity output.

Activating sequence factor 1 (ASF-1) is a nuclear DNA-binding activity that is found in monocots and dicots. It interacts with several TGACG-containing elements that have been characterized from viral and T-DNA genes, the prototypes of which are the as-1 element of the CaMV 35S promoter and the ocs element from the octopine synthase promoter. This class of cis-acting elements can respond to auxin and salicylic acid treatments. Consistent with these observations, we have shown that ASF-1 can interact with promoter elements of an auxin-inducible tobacco gene GNT35, encoding a glutathione S-transferase. Characterization of the nuclear factors that make up ASF-1 activity in vivo will be an important step toward understanding this induction phenomenon. The TGA family of basic-leucine-zipper (bZIP) proteins are good candidates for the ASF-1 nuclear factor. However, there may be as many as seven distinct TGA genes in Arabidopsis, five of which have now been reported. In this study, we expressed the cDNAs that encode four of these five Arabidopsis TGA factors in vitro and compared their DNA-binding behavior using two types of TGACG-containing elements. With specific antisera prepared against three of the five known Arabidopsis TGA factors, we also investigated the relative abundance of these three proteins within the ASF-1 activities of root and leaf nuclear extracts. Our results indicate that these TGA factors bind to DNA with different degrees of cooperativity and their relative affinity toward as-1 also can differ significantly. The results of a supershift assay suggested that only one of the three TGA factors represented a significant component of nuclear ASF-1 activity. Arabidopsis TGA2 comprises approximately 33 and 50% of the ASF-1 activity detected in root and leaf nuclear extracts respectively. These results suggest that each member of the TGA factor family may be differentially regulated and that they may play different roles by virtue of their distinct DNA-binding characteristics. Furthermore, since transcripts for each of these factors can be detected in various plant tissues, post-transcriptional regulation may play an important part in determining their contribution to nuclear ASF-1 in a given cell type.

Cochinmicins I, II, III are novel peptolides produced in submerged-fermentation cultures of Microbispora sp. ATCC 55140. These closely related compounds are separated by HPLC and are novel competitive endothelin antagonists. Cochinmicins II and III are stereoisomeric to each other. Cochinmicin I is the deschloro analog of cochinmicin III.

Cochinmicins I, II, and III are competitive endothelin antagonists produced by Microbispora sp. ATCC 55140. The cochinmicins are cyclic depsipeptides containing six alpha-amino acids and a pyrrolecarboxylic acid. Based upon MS, 1D and 2D NMR, and LC data, the structures and absolute stereochemistries of the cochinmicins have been assigned. All three components have the same basic sequence and contain one equivalent each of D-allo-threonine, D-alanine, L-phenylalanine, D-phenylalanine, 5-chloropyrrole-2-carboxylic acid (or pyrrole-2-carboxylic acid in cochinmicin I), plus two equivalents of 3,5-dihydroxyphenylglycine (DHPG). The phenylalanine residues were differentiated via a methanolysis product which contained only one of the phenylalanine residues. Both DHPG residues have the D configuration in the more active cochinmicins I and III. Cochinmicin II contains both D- and L-DHPG and these residues have been differentiated in the sequence based upon 1H NMR data.

A novel inositol mono-phosphatase inhibitor, L-671,776 (1), was discovered from a culture of the hyphomycete, Memnoniella echinata (ATCC 20928). 1 has a molecular weight of 388 and a molecular formula of C23H32O5. The mode of inhibition is non-competitive, with a Ki of 450 microM. It shows no inhibition of myo-inositol 1,4-bisphosphate 1-phosphatase or myo-inositol 1,4,5-triphosphate 5-phosphatase, although it weakly inhibits myo-inositol 1,4,5-triphosphate 3-kinase (IC50 = 3 mM). It elevates inositol monophosphates in rat parotid slices (EC50 approximately 3 mM), but abolishes agonist effects. It also produces short-lived contraction of guinea pig trachea at 300 microM.

The discovery and physico-chemical characterization of three novel and minor virginiamycin M1 analogs as potent gastrin antagonists from a culture of a strain of Streptomyces olivaceus are described. These analogs are L-156,586, L-156,587 and L-156,588. They are, respectively, 15-dihydro-13,14-anhydro-, 13,14-anhydro- and 13-desoxy-analogs of virginiamycin M1. We also chemically converted virginiamycin M1 (via L-156,587) to L-156,586 and its unnatural epimer, L-156,906. These analogs are competitive and selective antagonists of gastrin and brain cholecystokinin binding at nanomolar concentrations. These are the most potent gastrin/brain cholecystokinin antagonists from natural products. The same compounds showed poor Gram-positive antibiotic activity versus virginiamycin M1. Structurally related Gram-positive antibiotics, griseoviridin and madumycin I, were inactive in gastrin and brain cholecystokinin binding at up to 100 microM.

Tetrandrine, a bis-benzylisoquinoline alkaloid derived from the Chinese medicinal herb Stephania tetrandra, is a putative Ca2+ entry blocker whose mechanism of action is unknown. To investigate this mechanism, the effects of tetrandrine were characterized on binding of three chemical classes of Ca2+ entry blockers in cardiac sarcolemmal membrane vesicles. In the range 25-37 degrees C, tetrandrine completely blocks diltiazem binding, partially inhibits D-600 binding, and markedly stimulates nitrendipine binding, with greatest enhancement occurring at 37 degrees C. The potency of tetrandrine is increased 10-fold as temperature is raised from 25 to 37 degrees C. Scatchard analyses indicate that inhibition of diltiazem binding and stimulation of nitrendipine binding result from changes in ligand affinities while inhibition of D-600 binding is due to both an increase in KD and decrease in Bmax of aralkylamine receptors. Ligand dissociation studies reveal that tetrandrine increases D-600 off-rates, decreases nitrendipine off-rates, but has no effect on diltiazem dissociation kinetics. In addition, tetrandrine reversibly blocks inward Ca2+ currents through L-type Ca2+ channels in GH3 anterior pituitary cells. These results indicate that tetrandrine interacts directly at the benzothiazepine-binding site of the Ca2+ entry blocker receptor complex and allosterically modulates ligand binding at other receptors in this complex. These findings suggest that tetrandrine is a structurally unique natural product Ca2+ entry blocker and provide a rationale explanation for the therapeutic effectiveness of this agent.